UPPER TENNESSEE DRAINAGE. 579 



'41 (French Broad R., Tenn.), made synonyms by Simpson (pp. 122, 

 123). There are two specimens (J* and $) in the Walker collection, 

 labeled tener (from French Broad, Asheville, N. Car.). They are 

 rather thin-shelled, have rays, which are fine, and subcontinuous in 

 the male, but somewhat spotted in the female. They undoubtedly 

 are a form of E. nebulosa. 



U. simus Lea, '38 (Cumberland R., Tenn.) (Simpson, p. 123). 

 A male, with strongly developed rays : specimens of this type occur 

 frequently, and are practically identical with U. notatus^ admitted by 

 Simpson as a synonym of nebulosiis. 



This tremendous synonym indicates that we have to deal here 

 with a very variable species. The variation concerns first of all the 

 color pattern of the epidermis (rays). In the second line it is shown 

 in the color of the nacre, the shape of the shell, and, of course, some- 

 times the females have been made '' species " for the reason of their 

 different shape. It is not excluded that additional synonyms may be 

 discovered. 



E. nebulosa belongs in the affinity of E. iris (Lea), '30, and has 

 practically the same anatomy. Indeed, some of its forms are hardly 

 distinguishable from E. iris, and it may be that the latter is only the 

 western and northwestern representative of it (that of the Ohio 

 drainage). Thus it is also explained why iris has been recorded for 

 the upper Tennessee River (Lewis). 



According to my observations, there is only one species of the 

 im-group in the upper Tennessee region. It is generally an elon- 

 gated-elliptical shell, more or less pointed behind in the male, slightly 

 dilated and rounded posteriorly in the female, of a yellowish, green- 

 ish, or brownish color, covered more or less with rays, which nor- 

 mally are well developed, and very often broken up into spots. 

 These rays may be fine or wide (in the female, they are often very 

 broad and distinct on the dilated part of the shell), may cover all 

 of the shell, or only part of it, and may be indistinct or nearly miss- 

 ing. The interior of the shell may 'be white, or of all shades of 

 salmon, orange, pink, or purple. 



Although I have tried hard, I have been unable to separate this 

 group of forms into species, and it is also impossible for me to dis- 

 tinguish local races. It is true that sometimes specimens from a cer- 



